Fuel pressure responsive burner control system



8- 1947- F. s. AUBERT 2 FUEL PRESSURE RESPONSIVE BURNER CONTROL SYSTEI Filed Aug 25, 1941 2 Sheets-Shoot 1 12 FIG-1 '15 INVENTOR 3M 6. W

l- 1947- F. B. AUBERT 2,425,589

FUEL PRESSURE RESPONSIVB BURNER CONTROL SYSTBI Filed Aug. 25, 1941 2 Shoots-Shoot 2 mvsmon $2 6. m av M M ATTORNEY Patented Aug. 12, 1947 UNITED STATES PATENT OFFICE FUEL PRESSURE RESPONSIVE BURNER CONTROL SYSTEM Fred B. Aubert, Grosse Pointe, Mich. Application August 25, 1941, Serial No. 408,139

21 Claims.

This invention relates to new and useful improvements in control apparatus and more particularly to an apparatus for controlling the o eration of a fluid fuel burner.

An object of the invention is to provide a control apparatus which will be safe in operation.

Another object is to provide a burner apparatus having intermittent ignition in which ignition will be turned on when flame is absent at the burner.

Another object is to provide an electron discharge means for controlling operation of a relay included in the burner control apparatus.

Another object is to provide means to render the electron discharge means effective over a wide range of line voltage.

Another object is to provide means to stop operation of the burner upon excessive dissipation or drain of the negative charge on the control grid Of the discharge means.

Another object is to provide means to assure establishment of ignition prior to discharge of fuel at the burner.

Another object is to stop the discharge of fuel substantially instantly after a proper spraying pressure occurs, provided there is no ignition of fuel at the burner.

Another object is to provide a predetermined trial starting period for proper operation of the burner. v I

The invention consists in the novel system or apparatus and the cooperative relation of parts,

to be more fully described hereinafter and the novel features of which will be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a part of this specification, there is fully and clearly shown several preferred embodiments of the invention, in which drawings:

Figure 1 is a diagrammatic view of an oil burner control apparatus embodying the invention, and

Fig. 2 is a diagrammatic view of a similar apparatus but having certain changes in the operating circuits and showingcertain alternative con trol devices.

In the drawings, Figure l, numeral I designates a heating apparatus such as a boiler or furnace for heating a medium such as ,wateror air for direct use or for supplying heat to rooms and for other purposes. The heat exchange me dium in the heating apparatus is heated by a fluid fuel burner 2 such as an oil burner which will be of the gun or pressure type. The burner 2 has a combustion air discharge tube 3 and a cooperable fuel nozzle 4 for supplyinga comguided thrust rod 25 which is bustible mixture of air and fuel at the burner and within the combustion space of the heating apparatus I. The air tube or duct 3 is supplied with air by a fan or blower 5 driven by an electric motor 6 which also drives a fuel pump 1. A conduit or pipe 8 leads from a source of oil or other liquid fuel to the pump 1 from which a delivery pipe 9 leads to the nozzle 4. Intercalated in the pipe 9 there is a differential pressure and flow indicating means II] in the form of a hollow cylinder of non-magnetic material, having a pressure chamber II with an inlet I2 from the pump and an outlet I3 leading to the nozzle 4. Within the chamber l I there is a pressure responsive piston I4 of magnetic material serving as an armature and havin a, longitudinal fuel port or passageway therethrough into which a metering valve I5 extends to control flow through and to close the conduit 9. The valve l5 permits a slight leakage so that air will not be trapped in the oil line or conduit and to assure the spraying of oil from nozzle 4 upon the occurrence of pump discharge spraying pressure. A spring l6 regulates the movement of piston I4 by pump pressure and d termines the differential of fluid pressure in th conduit 9 on the opposite faces of piston I4 at which the piston I4 will be moved sufficiently into the magnetic field of a switch operating magnet I I to actuate and open the flow and pressure switch I8. The magnet I1 is secured to one end/0f a lever I9 which at its other end carries the movable contact 20 of the switch I8, the lever I9 being resiliently held in and urged to switch closed position by a spring 2 I. It should I be noted that ultimate metering is at the nozzle 4 and that there will be a back pressure against piston I4 acting in conjunction with spring I6 so that the piston is held in its magnet attracting position by a differential of fuel pressure.

A timer means including a low voltage rotary timer motor 22 having a drive shaft carrying switch operating cams 23 and 24 controls the starting of the burner motor 6 and also operates at the end of a'predetermined interval to stop operationof the motor 6 if a proper flame is not burning. The cam 23 has a or depression 25 within which seats one end of a forced out of the recess 25 immediately following energization and starting of motor 22, .to ride thereafter on the circumference of the cylindrical cam" for the remainder'of a substantially complete cam revolution. The thrust rod or member 26 by its longitudinal movement, on movement out of the recess 25, closes the holding switch 21 which is urged peripheral recess to open position by a spring 23. The switch 21 is thus held closed during the burner trial starting period or interval of rotation of cam 23. The cam 24 has one or more cam fingers 23 of which the first acts against the inclined cam surface 33 of a guided two-part thrust member 3| subsequent to and preferably immediately following the closure of switch 21. Endwise movement of member 3| by cam 24 acts to close the independently releasable pump motor switches 32, 33. The member 3| comprises rods 34 and 35 having a slip fit or lost motion connection therebetween. The switch 32 comprises a pair of resilient metallic switch arms or blades 35, 31 secured in spaced relation and at one end in a support 33 of electric insulating material. The blade 33 extends at its free end into a transverse slot in rod 34 so that the blade 35 is movable by and with the rod 34 to operate the switch 32. The blade 33 carries a contact 33 engageable with contact 43 of blade 31 upon operation of member 3| by cam 24, the resiliency of blades 33 and 31 permitting overtravel of the rod 34 upon switch closure and assuring a quick breaking of contact upon release of rod 34. Pivoted by a pin and slot or similar connection to rod 34, there is a armature lever 4| pivoted intermediate its ends and having its free end engageable with a stop 42 which may be adjustable to regulate the spacing of contacts 33 and .43 in open position, the lever being normally held against stop 42 by a spring 43. The free end of lever 4| also provides an armature cooperable with an electromagnet 44 which is ineffective to move the lever 4| from its open switch position but is operable to hold the lever 4| in its cam actuated position thereby maintaining switch 32 in closed position after release of rod 34 by cam finger 23. The stop 42 may also be adjustable to regulate the position of lever 4| relative to magnet 44 so that the magnet will be ineffective to close the switch 32. The switch 33 has resilient metallic arms or blades 45, 43 carrying contacts 41, 43 respectively, and secured in spaced relation at one end to the insulating support 33. The blade 45 extends at its free end into a transverse slot in the rod 35 so that upon take-up of the slight lost motion in member 3| the endwise movement of rod 35 by cam 24 will close switch 33. engaging contact 41 with contact 43. The resilience of blades 45, 43 permit overtravel of member 3| to assure closing of switch 33 and also provides a sharp break of contact engagement on switch opening movement. Also carried by the insulating support 33 there is a double throw switch comprising switches 43, 43 having resilient metallic arms or blades 53, 52 of which the switch operating blade 5| extends at its free end into a transverse slot in rod 35 for movement thereby and therewith. The blade 5| has opposite facing contacts 53, 54 cooperative respectively with contact 55 of blade 53 and contact 53 of blade 52. The resilience of blades 45, 45, 53, 5| and 52 likewise permits of a good contact make on switch closure and of a sharp break on switch opening. The rod 35 is held and urged toward a position to maintain switch 33 open, switch 43 closed, and switch 43 open by means of a coil spring 51 acting through an armature lever 53 pivoted intermediate at its ends and having one end connected by a pin and slot or similar connection as at 53, to rod 35. The rod 35 is limited in its movement toward cam 24 by means of stop 53 engageable with the free end of lever 53 and opposing spring 51. The free end of lever 53, upon closure of switch 33, opening of switch 43,

and closure of switch 43 is positioned in holding relation to an electromagnet 3i which is ineffective when energized to overcome spring 51, exerting a sufiicient force only to hold rod 35 in its cam actuated position. The stop 30 may be adjustable to regulate the position of lever 53 with respect to magnet 6| prior to operation of member 4| by cam 24 so that energization of the magnet 6| will not operate the rod 35.

The timer motor 22 is energized from the secondary low voltage winding 32 of a combined step-up and step-down transformer 53 having a primary windin 54 with its terminals connected to the main service line or lead wires 55, 55, preferably a volt circuit. The transformer 33 preferably has a shield 55' to block electrostatic flux but which will of course permit free passage or electromagnetic tiux. In the lead wire 33 there is a normally closed safety or limit switch 31 responsive to the heating apparatus temperature or pressure to break the main line circuit in the event of high or excess temperature or pressure of the heating apparatus. From the secondary 52, which may be 24 volts. a lead wire 33 extends to one terminal of a control switch 53 such as a room thermostat for controlling operation of the fuel burner. The switch 33 has a bimetal blade 13 connected to lead wire 33 and has a contact 1| engageable with a fixed contact 12 upon demand for increase of term perature by the thermostat. An electric resistance heater 13 is connected by a lead wire 14 to the other terminal of the secondary 52 and impresses a false ambient temperature upon the blade 13 to compensate for lag of response of the thermostat to increasing temperature change. The thermostat contact or terminal 12 is connected by a lead wire 15 to the switch blade 5| and through closed switch 53 and a lead wire 15 to the fixed contact of a closed relay switch 11 of a flame operated relay 13. The movable contact of switch 11 is connected by a. lead wire 13 to one terminal or the timer motor 22. From the other terminal of the motor 22 a lead wire 33 return to the transformer secondary 32.

The thermostat shunt switch 21 has its movable blade connected by a lead wire 3| to the transformer secondary lead wire 33. Theother blade or contact of switch 21 is connected by a lead wire 32 to the timer motor lead wire 13. From the lead wire 32 a branch lead wire 33 connects to the fixed contact of the flow switch |3. The holding magnet 44 is connected by a lead wire 34 to the movable contact 23 of flow switch l3 and is connected by a lead wire 35 to the transformer lead wire 33. The holding magnet 5| is connected to the open contact 53 of switch 43 by a lead wire 33 and has its other terminal connected by a lead wire 31 to the transformer secondary through return wires 35 and 33. From the limit switch terminal of transformer primary 54 a lead wire 35 connects to :he movable blade 45 of motor switch 33 which .1as its blade 45 connected by lead wire 33 to the double throw arm 33 of relay 13. The arm 33 engages the fixed contact of a switch "from which extend lead wires 32, 33, the lead wire 32 being connected to the movable arm 33 of motor switch 32 and the lead wire 33 being con.- nected to one terminal of the primary winding of an ignition transformer 34. From the other primary terminal of the transformer 34 a lead wire 35 connects to the main service lead wire 55. The secondary winding 33 of the ignition transformer is connected by lead wires to the spark or ignition electrodes 91 having their spark gap positioned in the path of the combustible mixture discharge from the burner. The motor switch 32 has its other witch arm 31 connected by a lead wire 98 to one terminal of the burner motor 6, the other terminal of which is con nected by a lead wire 99 to the lead wire 95 and thence to the service lead wire 65. The arm 90 of relay 18 is cooperable on relay energization to engage the fixed contact of a switch I from which a lead wire IOI extends to the terminal connection of burner motor 6 with lead wire 98, so that switch I00 is in parallel or shunt circuit with the motor starting switch 32. The relay 18 is controlled by an electron discharge means and has a relay coil I02 operable when energized to open the switches 11 and 9| and to close the switch I00. In circuit with the relay I02 there is an electronic tube or valve I03 in an electrical net work and having a plurality of control elec: trodes, namely an anode I04 and a cathode I05. The tube I03 may, for example, be one such as the 2050 Radiatron which together with hereinafter designated condensers has been found to provide satisfactory operation. Positioned between the anode and the cathode there is a screen grid I06 and a control grid I01, the cathode being heated by a filament heater I08. The relay coil I02 has one terminal connected by a lead wire I09 to the anode I04 and has it other terminal connected by a lead wire IIO to one terminal of the step-up secondary winding III, which may for example provide 142 volts, of transformer 53. The other terminal of winding III connects to a low voltage transformer winding II2 which may provide, say 6 volts. The terminals of the Winding II2 are connected by lead wires II3, II4 to the filament I08. Extending from the intermediate lead wire II4 which is connected at one end between windings III and H2, there is a lead wire II5 which connects to the cathode I05, the junction of lead wires H4 and H5 being connected to ground by lead wire II6. Extending from the screen grid I06 there is a lead wire II1 which is secured to one plate or side of a fixed condenser II8 which may, for example, have a capacity of 100 M. M. F. From the other plate or side of condenser II8 lead wire II9 connects to the control grid I01. This lead wire I I9 is connected by a lead wire I to the cathode of a photoelectric cell I2I which has its anode connected to ground by lead wire I22. The cell I2I is housedin a light eliminating casing I23 having a light ray admitting tube I24 opening thereinto'. The tube I24 is focused on the cell I2I for impingement thereon of light rays from the burner flame, the tube eliminating transmission to the cell of extraneous light rays. The cell I2! is preferably one which will respond only to thel'iigher wave bands and will not be rendered conductive by wave lengths at the lower end of the spectrum. The transformer lead wire II3 which connects to the filament has a branch lead wire I connected to one plate or side of a condenser I26 which has its other plate or side connected by a lead wire I21 to the screen grid lead wire- II1, the condenser I26 having, for eX- ample, say a capacity of 200 M. M. F. The fore going net work also compensates for variations in line voltage so that with a normal 110 volt circuit, the system will function over a range from about 80 volts to 135 volts. This compensation results from the characteristics of the valve I03 in relation to the condensers II8, I26 and the winding of transiermer secondary I I2,

The operation of the burner control apparatus is as follows: When the room thermostat 69 calls for heat upon a-decrease of room temperature so as to'engage contact H with contact 12, the manualt'svjoit'ch 68 from the transformer being closed, current will flow from the transformer secondary 62*through leadtiv-ire 88, the thermostat 69, lead wire'15, closed switch 49. lead Wire 16, closed relay switch 11, lead wire 19 to the timer-means or motor 22 and thence via lead wire back to the transformer secondary 62. The energization of motor 22 will rotate cams 23 and 24. Initial rotation of cam 23 will act through thrust rod 26 to close the timer motor maintaining switch 21 within a few degrees of rotation or a few seconds afterienergization of motor 22, so that the room thermostat 69 willbe shunted and thus rendered ineffective to stop the timer motor until its cycle is completed. Closure of switch 21 will cause current to flow from the transformer secondary 62 through lead wires 68 and 8| to the closed switch 21 and thence via lead wire 82 to the timer motor lead wire 19 thus maintaining the motor 22 in operation for a complete revolution or cycle of cam 23 which may be timed to cover a burner trial starting interval of say two minutes. Upon lapse of this interval, the cam recess 25 will again come into line with thrust rod 26 so that spring 28 will open the switch 21 as it moves rod 26 into the recess, thereby breaking the holding circuit 8I, 82 for the timer motor. This opening of switch 21 will stop the timer motor due to prior breaking or interruption of the room thermostat timer motor circuit as will be hereinafter described. During the interval of rotation of cam 23 and within a few seconds after closure of switch 21, the finger 29 of cam 24 will engage the cam surface 30 of thrust member 3| and move switch 32 of the two motor starting switches 32, 33 to closed position. This cam operation of rod 34 will rotate lever 4i into holding relation to magnet 44 which was energized upon closure of room thermostat 69 and is held energized by closure of shunt switch 21, its circuit bein from switch 21 through lead wires 82 and 83 to the closed flow switch I8 and thence to one of the magnet terminals by lead wire 84, the holding magnet circuit being completed to the transformer secondary 62 through lead wires and 80. When the lost motion between thrust rods 34 and 35 has been taken up which may occur prior to closure of switch 32, the continued endwise movement of the thrust member 3| by cam finger29 will close the second switch 33 of the jrnotor s'tartingswit'ches and will break circuit at switch 49 of the thermostat timer motor circu i and will also close'contacts 54, 56 of switch 49. "to blish the circuit of holding magnet 6I from the r'oomither'mostat 69 through lead wire 15 to switch v49;'elr'rd thence to one terminal of the the magnet 6!. by. lead wire 86, the circuit continuing from magnet 6| through lead'wires 81, 85 and 80 to the transformer secondary 62. The armature lever 58 is positioned in holding relation toynia'gnct 6| by this cam operation of thrust rod 35 so that the motor switch 33 and the contacts 54, 56 of switch 49 are held closed under the control of the room thermostat 69, the magnet 6I serving to maintain its own energization circuit through contacts 54, 55 due to its holding of armature lever 58 in actuated position. Closure of motor switches 32, 33 will thus establish a high voltage circuit from the service line through the flame controlled relay 18 to the burner motor 6 follows: From main lead wire 66 through safety limit control 01, lead wire 00, closed switch ll. lead wire 08, relay arm and switch 0|, lead wire 02 to and through closed switch 32, lead wire 00 to one terminal of motor 0 and thence from the other motor terminal, through lead wires 09 and 05 to main lead wire 05. Operation of motor 6 will drive the pump I to draw fuel from the source of supply through conduit 8 and discharge the liquid fuel through condut 9 to the control device I0, building up pressure in the chamber II against piston I4. As the pump discharge pressure builds up, piston 49 will be moved against the force of spring I6 and fuel will feed through the valve I5 to nozzle 4. When the fuel pressure in chamber II on piston I4 has increased to the desired spraying pressure which is indicative of an ignitable discharge of fuel at the nozzle 4, the piston I4 will have been moved to a position below magnet I! at which the magnetic force will have actuated switch I0 to open position. The closure of switch 03 also completed ,the ignition circuit through closed relay switch 0i and thence via lead wire 00 to the primary of ignition transformer 94. Therefore. at the time of energization of burner motor 0, the transformer 84 was likewise energized so that high tension current from the ignition transformer secondary 00 will be fed to the spark electrodes 91 thus providing a continuous ignition spark prior to discharge of fuel spray from nozzle 4. Therefore, the fuel mixture discharged at the burner by the combined action of fan 5 and pump I will, if ignitable, instantly be ignited by the ignition spark substantially coincident with the opening of switch I! to deenergize holding magnet 44 so that spring 40 will return the thrust rod 04 to the position shown thereby opening the motor starting switch 32 which will break the only then existing circuit to motor 8. The occurrence of flame at the burner is however instantly recognized by the electron discharge means controlling the relay I8, which when energized, shunt circuits the switch 02 by closure of relay switch I00 thereby providing a. motor reenergization or maintaining circuit from motor switch 33 through lead wire 0!, closed switch I00 and lead wire IM to the motor I. The flame responsive energization of relay coil I02 normally occurs substantially instantaneously with opening of flow switch 20 so that no hesitation of pump operation occurs. Since the control device I0 requires a building up of pump pressure to the desired spraying pressure before permitting flow to the nozzle 4. as above described, and as this spraying pressure is that at which switch I8 is opened, the circuit for the burner motor 6 is broken before or substantially as the fuel is isnited. However, the inertia of motor rotation will carry or hold over the pump pressure, permitting some time lag, so as to maintain the pump spray discharge until coil I02 closes the alternate motor circuit switch I00. Therefore the starting circuit for the motor 6 is preferably broken before the operating motor circuit is completed through switch I00, without the control system blocking itself out resulting from failure to pick up flame. Upon the occurrence of a proper flame at the burner, the light rays from the flame acting on cell I2I will reduce the resistance of the cell to current flow, so that the negative charge on grids I06 and I01 will be partially dissipated or leaked to ground thereby rendering the control grid I0I sufficiently less negative, i. e. more positive, so that the electron dis charge from the cathode I05 to the anode I04 will permit current flow through the relay I02 from the transformer secondary III. Energization of relay coil I02 by current flow through tube I00 will act to open relay switches I1 and III and close the relay switch I00. If the control grid I0! is shorted to ground by a short circuit from lead wire I20 or if cell I2I becomes shorted, then the.

full negative bias will be applied to the screen grid I06 thus blocking electron discharge to the anode and deenergizing the tube or valve I00. Should such a short circuit occur during operation of the burner and subsequent to lapse of the trial starting period after magnet'44 has been deenergized, the circuit of motor 0 will be broken at the switch I00 and ignition will be instantly reestablished by closure of switch 9|. Should there be a flame failure for any reason after closure of switch I00 by relay coil I02 such as to deenergize the relay coil, or should the relay coil become deenergized for any reason, the switch I00 will instantly be opened thereby stopping the burner motor 8 and as above noted, simultaneously establishing reignition at the spark electrodes 91.

In order to restart the burner motor 0 the timer motor 22 must again be placed in operation. Since the timer motor shunt circuit is open at the switch 21 and the thermostat timer motor circuit is open at contacts 53, of switch 49, the thermostat circuit controlling the holding magnet BI must be broken in order to close switch contacts 53, 55. The holding magnet may be deenergized by opening the manual switch 08 which may be located adjacent the burner if desired, or by normally opening the room thermostat contacts by reducing its temperature setting. If now the switch or the room thermostat contacts are again closed, a timermotor circuit through switch 49 will be completed to initiate the burner trial starting period as above described. If more than one cam finger 20'is provided, then should there be a flame failure during the starting interval such that relay coil I02 becomes deenergized, the relay switch 9I would be closed thereby stopping operation of the burner motor 6 until the second or subsequent cam finger 20 engaged the rod cam surface 30 to close switch 32, the switch 03 of course remaining closed since the circuit of holding magnet 0| has not been opened at the switch contacts 54, 50. During this retrial of burner starting, the ignition would of course be on by reason of closure of switch 9| when flame failed, so that an igniting spark would be present should the fuel spraying pressure again be reached prior to completion of rotation of cam 23 so that the sprayed fuel would be ignited, then recognition of flame as above described would energize relay I02 and close the burner motor switch I00, deenergizing the ignition transformer and shunting the motor switch 32 as above described.

The thermostat 69 may be so constructed that upon prolonged continuous energization of heater I3 upon a call for heating by the thermostat and such as would occur on failure of the heat supply from the heating apparatus, the heater 13 will generate sufficient heat to cause the room thermostat to be opened automatically thereby deenergizing its resistance heater I3 and the holding magnet 6|. When the blade I0 cools due to discontinuance of heat from resistance I3, the circuit will again be made at contacts I I, I2 thereby automatically restarting the burner. If, therefore, burner motor 6 is stopped by reason of flame failure, the system will, after timer motor 22 has completed its burner starting cycle, be automatically restarted by the automatic opening and closing of the room thermostat 69.

When the room thermostat 69 becomes satisfied thereby separating contacts H, 12 or if these contacts, after motor 22 stops, or either of the switches 61 or 68 are opened for any reason, the burner motor 6 will be stopped, because the motor switch controlling magnet 6I will be deenergized. Stopping of the burner will place the system in condition for restarting as soon as the pump pressure decreases sufliciently to permit closure of flow switch I8 by spring 2 I.

Referring to the control apparatus or system of Fig. 2, there is a heating apparatus I30 such as a boiler or furnace for supplying heating medium to a room or other space and having a liquid fuel burner I3I controlled by a main control switch or room thermostat I32 responsive to the temperature of the mdium which is heated either directly or indirectly by the heating apparatus I30. The burner I3I has an electric motor I33 which drives an oil pump I34 and a fan or blower I35 for supplying combustion air through the burner tube I36 into the combustible chamber. The pump I34 draws fuel from an oil tank through conduit or pipe I31 and discharges it through pipe I38 to the burner nozzle I39. A pressure responsive switch I40 is operated by a pressure responsive element I M such as a metallic bellows having its interior connected into the pump discharge pipe I38. The switch I40 is urged toward open position to maintain the switch contacts I42, I43 normally in separated relation. The bellows I4I acts to close switch I40 at a predetermined pressure in conduit I38 which is indicative of a discharge of fuel at ignitable spraying pressure from nozzle I39.

A timer means or motor I44 acts when energized to drive switch operating cams I45, I46 and I41. The cam I45 acts immediately at the start of its rotation'to close a circuit holding or maintaining switch I48 to keep motor 22 in operation for a complete revolution, the switch I48 beingin shunt circuit with the thermostat switch I32. The cam I45 operates to close the switch I48 through a guided thrust rod I49 against the force of a switch opening spring I50, the rod I49 seating when motor 22 is deenergized in a cam recess II. The rotation of cam I45 forces the thrust rod out of recess I5I and on to the cylindrical cam surface thereby closing switch I48, the thrust rod I49 riding on the cylindrical surface through the remainder of rotation of cam I45 which covers a predetermined interval or period of say two minutes. When the cam I45 has completed its rotation, the spring I50 will move thrust rod I49 into recess I5I thereby opening the switch I48 and stopping the motor 22 as the thermostat circuit to motor 22 will then have been broken. The cam I46 has a cam finger I52 engageable' with the inclined cam surface I53 of a guided switch operating thrust rod I54 operatively connected to a motor starting switch I55, a timer motor starting switch I56 and a holding magnet control switch I51. The switch I55 has a resilient operating arm or blade I58 carried by a supporting member I59 of electric insulating material and extending'at its free end into a "transverse slot in rod I54. The blade I58 carries a contact I60 normally spaced from and cooperable with a contact I6I carried by a resilient switch arm or blade I62 secured to the supporting member I59. Switches I58 and I51 have a common resilient operating arm or blade I83 carried by the supporting member I59 and having its free end extending into a transverse slot in the rod I54. The blade I63 carries oppositely directed contacts I64, I65,forming part of switches I56, I51 respectively. 'The contact I84 is normally in engagement with a contact I66 carried by a resilient switch arm or blade I61 secured to the supporting member I59. The contact I85 is spaced from but engageable with a contact I68 of a resilient switch arm I69 secured to the supporting member I59. A pivoted armature lever I10 has a pin and slot or similar connection to the rod I54 and has a spring I1I acting thereon to hold its free end against an abutment member or stop I12 which limits the movement of rod I54 toward cam I46 and determines the position of switch arms I58 and I63. The free end of lever I10 acts as an armature for coopera tion with an electromagnet I13 which when energized, is ineffective to overcome spring I1I, but has sufficient holding force to hold the lever I10 in its cam operated position against the force of spring IN. The cam I41 acts on a twopart thrust member I14 having aligned guided thrust rods I15, I18 between which is positioned a displaceable thrust transmitting ball I11. The thrust member I14 is longitudinally moved by the cam I41, the rod I15 seating in a cam recess I18 out of which the rod is forced upon rotation of the cam I41 to thereafter ride on the cylindrical cam surface until the cam completes its rotation when the return spring I19 will reseat the rod I15 in recess I18. Longitudinal movement of member I14 by cam I41 will position the ball I11 in alignment with an operating pin I which may be operated by an electromagnet I8I to force the ball I11 upward against the force of a spring I82 and out of abutting force transmitting relation to the end of thrust rod I16. The thrust rod I16 is opera tively connected to a releasable burner motor starting switch I83 having a resilient switch arm or blade I84 secured to a supporting member I85 of electric insulating material. The free end of blade I84 extends into a transverse slot in the I16 so that on longitudinal movement of thrust member I14 by cam I41, a contact I85 on arm I84 is engaged with the contact I86 on a resilient arm or blade I81 carried by the supporting member I85 thereby closing switch I83. A spring I88 opposing cam operation of rod I16 acts to move switch I83 to open position upon displacement of ball I11 by pin I80. When cam I41 completes its rotation so that rod I15 is again seated in recess I18 by spring I19, the ball I11 will be carried therewith and be forced by spring I82 into its longitudinal endwise relation to and between rods I15, I18.

The fuel igniting means includes a high tension ignition'transformer I89 having a primary wind-, ing I90 and a secondary winding I9I which is connected by lead wires to the spark electrodes I92 having their gap positioned in the path of the combustible mixture from nozzle I39 and the air tube I36.

The ignition transformer primary winding I90 is controlled by a flame operated relay I83 having an operating coil I94, which when energized. acts to open the closed relay safety switch I95 and the closed ignition switch I96. One contact of the ignition switch is carried by a relay arm I91 which also carries the movable contact I98 of an open burner motor switch I99 in shunt or Q ondary winding 238 of transformer 220.

parallel circuit with the motor starting switch I83. The relay coil I64 is controlled by an electron discharge means 200 included in an electric network "I. an electronic valve or tube 202 and an electrostatic discharge electrode 203 cooperable with the burner flame. The electronic valve 202 has an anode 204 separated from the cathode 205 by a screen grid 206 and a control grid 201. A filament heater 200 for the cathode has one side electrically connected as at 209 to the cathode and has its other side connected to one side or plate of a condenser 2I0 which has its other side or plate connected to the control grid 201. The control electrode 203 is electrically connected by a lead wire 2 to the control grid 201 and its side of condenser 2I0. The filament heater 200 is energized by a transformer 2I2 having its low voltage secondary 2I3, Ol' say 6 volts, connected by a lead wire 2l4 to the illament and cathode 200. The other side of transformer 2I3 is connected by a lead wire 2I5 to the remaining filament terminal and the filament side of condenser IN. The screen grid 200 is connected to ground by a lead wire III. From the lead wire 2I6 a lead wire 2" connects the screen grid 206 to the cathode and filament lead wire 2. From the Junction of lead wires 2I4 and M1 and their connection to the cathode 205 there is a lead wire 2I8 extendin to the secondary winding 2I9 of a transformer 220. From the other side of transformer secondary 2I9 a lead wire 22I extends to one. terminal of the relay coil I34. the other terminal of coil I 94 being connected by a lead wire 222 to the anode 204.

The control apparatus is supplied with current from main line or service lead wires 224, 225, the wire 224 being connected to one side or terminal of a safety or limit switch 226 responsive to temperature or pressure of the heating apparatus I30. From the other side of switch 226 a lead wire 221 connects to one terminal of the primary 220 of transformer 220 and a second lead wire 229 connects to the fixed blade I62 of burner motor startin switch I55. The other terminal of transformer primary 226 is connected by a lead wire 230 to the service wire 225. From the cam operated switch arm I58 of the burner and ignition switch I55 a lead wire 23I extends to the relay arm I91. From the fixed contact of relay switch I96 a lead wire 232 connects to one terminal of the ignition transformer primary I90 which has its other terminal connected by a lead wire 233 to a lead wire 234 extending from the service wire 225 to one terminal of the burner motor I33. From the other terminal of motor I33, a lead wire 235 connects to the fixed contact of relay switch I93. The motor starting switch I83 is in parallel or shunt circuit with the relay switch I99 and has its cam operated arm I04 connected by a branch lead 236 to the lead wire 23I and has its fixed contact arm I31 connected by a lead wire 231 to the motor lead wire 235.

The timer motor I44 is energized from the sec- From one terminal of the transformer secondary 230, a lead wire 239 extends to the temperature responsive element 240 of switch I32 and contains a normally closed manual switch 24I. From the fixed contact 242 of switch I3I a lead wire 243 connects to the cam operated arm I63 of the double throw switches I56, I51. From the fixed contact arm I61 of switch I56 a lead wire 244 extends to the fixed contact of relay switch I95. From themovable contact of switch 95 a lead wire 249 to the timer motor feed wire 245. The

room thermostat I32 is preferably provided with a compensating resistance heater 250 which is electrically connected to the thermostat contact 242 and which connects by a lead wire 25I to the transformer secondary 236 via the timer motor lead wire 246. The coil of holding magnet I13 has one terminal connected by a lead wire 252 to the fixed arm I69 0! switch I51 and has its other terminal connected by a lead wire 2" to the transformer secondary 230 via the timer motor lead wire 246. The thrust member release magnet III has one terminal of its coil connected by a lead wire 254 to the timer motor lead wire 240 and has its other terminal connected by a lead wire 255 to the movable contact I42 of pressure operated switch I40. From the fixed contact I43 of pressure switch I40 9. lead wire 256 connects to the lead wire 239 on the transformer side of switch 24I. The filament transformer 2I2 has its primary connected across'the service wires 224, 225 by lead wires 251, 258 respectively.

The operation of the control system or apparatus of Fig. 2 is as follows: Upon closure of the control switch I32 as by a demand for temperature increase, the limit switch 226 and manual switch I being closed, a low voltage circuit will be established from the transformer secondary 233 through lead wire 239 and closed switch I32 to lead wire 243, thence through closed timer starting switch I56, lead wire 244, closed safety relay switch I95, lead wire 245 to the timer motor I44 and through lead wire 246 back to the transformer secondary 238. The closure of switch I32 will also energize the compensating heater 250 to impress a false ambient temperature on the responsive element 240 so as to compensate for lag in response of the element 240 thereby 'preventing overheating of the room or other space by the heating apparatus I30. Initial rotation of the cam I45 by motor I44 will within a few seconds of energization of motor I44, close the timer motor holding switch I46 for a predetermined burner trial starting period. The closure of switch I46 completes a shunt or parallel circuit around the control switch I32, the circuit being from trans'ormer secondary 238 through lead wires 239 and 241 to switch I43 and thence via lead wires 249 and 245 to the timer motor I44, the lead wire 246 completing the circuit from the timer motor back to the transformer secondary 238. Simultaneously with or directly following closure of switch I43, the cam finger I52 will engage the thrust rod cam surface I53 and move the thrust rod I54 against the force of spring I1I thereby closing the motor starting switch I55, opening the timer motor starting circuit at switch I56 and closing the circuit for the holding magnet I13 at switch I51. The thrust rod I54 will therefore be held in its operated position by the magnetic forc of electromagnet I13 on armature lever I10, the magnet I13 thus having its transmitting relation to thrust rod I16.

13 member I14 against the force of springs I19 and I68 to close the motor starting switch I03. The circuit to the burner motor I33 will thus be completed as follows: From service wire 224 through limit switch 226. lead wire 229, closed motor switch I55, lead wires 23I and 236, closed motor starting switch I03, lead wires 231 and 235 to one terminal of the motor I33 and thence from the other mtor terminal via lead wire 234 to service wire 225. The closure of motor switch I55 will also establish ignition at the burner through the closed ignition relay switch I96 which is in parallel with the motor switch I83, the circuit being from closed motor switch I55 via lead wire 2'3I, closed ignition relay switch I96, lead wire 232, to one ter minal of the ignition transformer primary I90 and thence from the other primary terminal via lead wire 233 to lead wire 234 which connects to the service wire 225. The operation of the burner motor I33 will drive the blower I35 and the pump I34 and when the pressure in the pump discharge conduit I30 has increased to the desired spraying pressure, the pressure responsive bellows I will close switch I40 thereby energizing the actuating magnet I8I which has its circuit com-' pleted as follows: From transformer secondary 238 via lead wire 256, closedpressure switch contacts I43 and I42, lead wire 255, to the coil of magnet IOI and thence via lead wire 254 to lead wire 246 connected to the transformer secondary 238. Energization of magnet I8I will move pin I80 upward against thrust ball I11 which has been moved into overlying relation with the pin I80 by cam I41. The pin I80 will force the ball I11 upward out of holding relation to thrust rod I16 so that spring I88 will move rod I 16 toward the left to the position shown, thereby opening the motor switch I83. When cam I41 completes its rotation, spring I19 will move thrust rod I15 to the position shown in cam recess I18 and spring I82 will move ball I11 back into thrust The switch I83 will only be opened during the burner trial starting interval providing the desired fuel spraying pressure has been built up by pump I34 to close the switch I40. The occurrence of this spraying pressure which will close switch I40, causes discharge of an ignitible spray at nozzle I39 for mixture with the combustion air discharge from tube I36. The combustible mixture will be instantly ignited by the continuous ignition spark between electrodes I92 which was established simultaneously with energization of motor I33.

Therefore, although the burner motor circuit is broken at the switch I33, occurrence of flame will be instantly recognized by the electronic discharge means 200 which will complete the circuit' of relay coil I94 thereby closing the motor shunt switch I99. The closure of switch I99 will maintain energization of or will reenergize the burner motor I33 with substantially no loss of pump discharge pressure so that the flame established will continue without interruption.

The electronic valve 20I has its control grid negatively charged during positive charge of the anode 204 by reason of the condenser connection 2I0 between the control rid 201 and the filament heater circuit. When, however, operation of the burner provides a flame of proper mass, the

electrostatic discharge from electrode 203 will leak off or dissipate suflicient of the negative control grid charge to render the valve 20I conductive and sufllcient current will flow through the relay coil I94 from transformer secondary 2I'3 to actuate switches I and I96 to open position and to close the burner motor switch I99.

Should the pump I34 fail to build up suflicient pressure by reason of lack of oil, air leakage or other reasons, or should the switch I40 fail to close during the burner starting interval, then upon lapse of the starting interval, the magnet I8I not having been energized, the thrust member I14 will be returned to the position shown thereby opening switch I83 and stopping further operation of the burner motor I33. Continued operation of timer motor I44 will also be stopped since substantially simultaneously with such opening of switch I83 the timer motor holding switch I48 will also be opened. In order to restart the burner motor the holding magnet I13 must be deenergized which may be accomplished by opening of switch 24I in the thermostat circuit or manually opening the thermostat switch I32 which by deenergizing the magnet I13 will release rod I54 from its held position thereby opening the switches I55 and I51 and closing the timer motor starting switch I56. The burner may then be restarted as above described by.

closure of control switch I32 or manual switch 24I, whichever had been opened.

Should there be a flame failure or should the flame mass decrease so as to build up a negative blocking charge on control grid 291 sufflciently to deenergize relay coil I94, then the motor switch I99 will be moved to open position and the ignition switch will be closed. Since switch I83 will have been opened by operation of the magnet I8I on bail I11, the opening of switch I99 will stop the burner motor I33 but ignition will immediately be established by closure of switch I96. The timer motor I 44 if still energized, will continue in operation until the burner starting interval has been completed when it will stop itself by opening of its circuit at switch I48. Restarting of burner operation is thereafter accomplished by the opening and subsequent closing of switch 24I or of the control switch I32 as above described.

Should there be a failure of flame or the flame mass decrease such as to deenergize the relay coil I94 after lapse of the starting interval of operation of timer motor I44, then the deenergization of relay coil I94 will stop the burner motor I33 and instantly reestablish ignition as last described. The restarting of the burner will, as above described, require the opening and subsequent closing of either the manual switch 24I or the control switch I32.

It may be noted that the negative control grid charge of valve I03 may be dissipated on the pccurrence of flame mass by an electrostatic discharge electrode such as described in connection with Fig. 2. Such an electrode, however, has certain disadvantages which are overcome by the use of the cell I2I. The electrode is more sensitive to variations in the flame characteristics, is more subject to short clrcuiting due to necessary wiring and is less convenient of installation. The

use of such an electrode also requires a reduction 1. In a fluid fuel burning apparatus, a, burner,

a motor, means driven by said motor to supply fuel to said burner, means to ignite the fuel discharged at said burner, means actuated substantially coincident with the discharge of an ignitable amount of fuel from said burner to deenergize said motor to ultimately deactivate said fuel supply means, and means operable substantially coincident with ignition of the fuel to further establish the supplying of fuel.

2. In a fluid fuel burning apparatus, a burner, a motor, means driven by said motor to supply fuel to said burner, means to ignite the fuel discharged at said burner, means operable substantially coincident with the discharge of an ignitable amount of fuel from said burner to deenergize said motor to ultimately deactivate said fuel supply means, and electronic tube control means responsive to occurrence of flame at said burner and operable substantially coincident with occurrence of flame to further establish the supplying of fuel.

3. In a fluid fuel burning apparatus, a burner, a motor, means driven by said motor to supply fuel to said burner, means to ignite the fuel discharged at said burner, means operable substantially coincident with the discharge of an ignitable amount of fuel from said burner to break a circuit for said motor to ultimately deactivate said fuel supply means, and photo-electric means responsive to occurrence of flame at said burner to further establish the supplying of fuel.

4. In a fluid fuel burning apparatus, a burner, a motor, means driven by said motor to supply fuel to said burner, means to ignite the fuel discharged at said burner, means operable substantially coincident with the discharge of an ignitable amount of fuel from said burner to break a circuit for said motor to ultimately deactivate said fuel supply means, electron discharge means having a network, means operable by said discharge means to further establish operation of said fuel supply means substantially simultaneously with the breaking of said circuit, and a static discharge electrode cooperable with an operating flame mass to render said discharge means operable.

5. In a fluid fuel burning apparatus, a burner, a motor, means driven by said motor to supply fuel to said burner, means to ignite the fuel discharged at said burner, means operable upon the discharge of an ignitable amount of fuel from said burner to deenergize said motor to ultimately deactivate said fuel supply means, and means operable substantially coincident with ignition of the fuel and deenergization of said motor to establish a circuit for continuing the operation of said motor and to discontinue operation of said igniting means.

6. In a fluid fuel burning apparatus, a burner, a motor, means driven bysaid motor to supply fuel to said burner, means to ignite the fuel discharged at said burner, means actuated by and directly controlling fuel flow to said burner and operable upon actuation to break the motor circuit to ultimately deactivate said fuel supply means, and means operable upon ignition of the fuel to establish a circuit for maintaining operation of said motor.

7. In a liquid fuel burning apparatus, a burner, a pump for supplying liquid fuel under pressure to said burner, means to drive said pump, means to ignite the fuel discharged at said burner, means operable upon occurrence of predetermined fuel pressure to deenergize said pump driving means, and means responsive to the fuel flame at said burner to energize said pump driving means to continue the supplying of fuel.

8. In a liquid fuel burning apparatus, a burner having a fuel supply conduit, a pump for supplying fuel under pressure to said conduit, an electric circuit for said pump, means to ignite the fuel discharged at said burner, a timer motor. means including a running switch operable by said timer motor to energize said igniting means and to start operation of said pump, a switch operable by said timer motorand controlling said electric circuit and operable upon expiration of a predetermined interval of timer motor Operation to stop operation of said ,pump, a main switch, electromagnetic means energized by 010' sure of said main switch and by operation of said timer motor and operable to hold said running switch closed upon initial closure of said running switch by said timer motor, and means responsive to occurrence of flame at said burner and opera-- ble to maintain operation of saidpump beyond said interval to establish a circuit in cooperation with said running switch and simultaneously to stop operation of said igniting means.

9. In a liquid fuel burning apparatus, a burner, a pump for supplying fuel under pressure to said burner, a timer motor. a switch closed by said motor to maintain operation of said motor for a predetermined interval, a pair of pump controlling switches in series circuit and closed by said motor, means to hold one of said pump switches closed, means to ignite the fuel supplied to said burner, a relay having an open pump switch in parallel with the other of said pump switches, means responsive to a fuel pressure indicative of discharge of an ignitable supply of fuel at said burner and operable to open said other of said pump switches, and means instantly acting upon flame at said burner to operate said relay to close said open relay switch thereby to maintain operation of said pump.

10. In a liquid fuel burning apparatus, a burner, a pump for supplying fuel under pressure to said burner, a timer motor, a switch closed by said motor to maintain operation of said motor for a predetermined interval, a pair of pump controlling switche in series circuit and closed by said motor, means to hold one of said pump switches closed, means to ignite the fuel suppliedto said burner, a relay having an open pump switch in parallel with the other of said pump switches, said relay having a closed ignition switch controlling said igniting means, means responsive to a fuel pressure indicative of discharge of an ignit-' able supply of fuel at said burner and operable to open said other of said pump switches, and means instantly acting upon flame at said burner to operate said relay to open said ignition switch and to close said open relay switch thereby to maintain operation of said pump.

11. In a liquid fuel burning apparatus,'a burner, a pump for supplying fuel under pressure to said burner, a timer motor, a switch closed by said motor to maintain operation of said motor for a predetermined interval, a pair of pump controlling switches in series circuit and closed by said motor, magnetic "means energized by operation of said motor and acting to hold one of said pump switches closed, means to ignite the fuel supplied to said burner, a relay having an open pump switch in parallel with the other of said pump switches, means responsive to a fuel pressure indicative of discharge of an ignitable supply of fuel at said burner and operable to open said other of said pump switches, means instantly acting upon flame at said burner to operate said relay to close said open relay switch thereby to maintain operation of said pump, and means to deenergize said magnetic means to stop operation of said pump.

12. In a fluid fuel burner control apparatus, a burner motor, a circuit for said motor, a motor starting switch for said circuit, means to close and then to open said switch, electricfuel ignition means, a circuit for saidignition means, a closed relay switch controlling said motor circuit and said ignition means circuit, an open relay switch operable to close a second circuit to said motor, and electron discharge means instantly responsive to a burner operating flame and con trolling said relay switches to open said closed switch to break said ignition means circuit and said first named motor circuit and to close said open switch to maintain operation of said motor after said starting switchis opened.

13. In a fluid fuel burner control apparatus, a burner motor, a burner switch operable to close a circuit to said motor, electric fuel ignition means, a closed relay switch controlling said circuit and said ignition means, an open relay switch operable to close a second circuit to said motor, means responsive to a fuel pressure and fuel flow indicative of an ignitable fuel discharge, means controlled by said pressure and flow responsive means and operable to open said burner switch,

and electron discharge means instantly responsive to a burner operating flame and controlling said relay switches to open said closed switch to deenergize said ignition means and to close said open switch to energize said motor.

14. A fiuid fuel burner control apparatus comprising a burner, a room thermostat, a timer motor, a current source for supplying saidtimer motor and controlled by said room thermostat, a closed timer motor switch in circuit with said thermostat and opened by operation of said timer motor, an open timer motorlswitch shunting said thermostat and closed by said timer motor prior to opening of said closed switch, a burner motor, a pair of open burner motor controlling switches in series circuit, means operable by said timer motor to close said burner switches upon opening of said closed switch, a holding magnet for maintaining one of said burner switches in closed position and controlled by said room thermostat, a holding magnet for maintaining the other of said burner switches in closed position and controlled by said open timer motor switch, a switch responsive to a fuel pressure indicative of discharge of an ignitable supply of fuel at said burner and operable to deenergize said secondnamed magnet, means to ignite the fuel discharged at said burner, and means responsive to occurrence of flame at said burner and operable to discontinue operation of said igniting means and to establish a burner motor circuit from said one of said burner switches.

15. A fluid fuel burner control apparatus comprising a burner, a room thermostat, a timer motor, a current source for supplying said timer motor and controlled by said room thermostat, a closed timer motor switch in circuit with said thermostat and opened by operation of said time motor, an open timer motor switch shunting said thermostat and closed by said timer motor prior to opening of said closed switch, a burner motor, a pair of open burner motor controlling switches in series circuit, means operable by said timer motor to close said burner switches upon opening of said closed switch, a holding magnet for maintaining one of said burner switches in closed position and controlled by said room thermostat, a,-holding magnet for maintaining the other of said burner switches in closed position and controlled by said open timer motor switch,

a switch responsive to a fuel pressure indicative of discharge of an ignitable supply of fuel at said burner and operable to deenergize said secondnamed magnet, means to ignite the fuel dis charged at said burner, a relay having a closed switch in series with said one burner switch and controlling current flow to said igniting means and to said other burner switch, said relay having an open switch in series with said one burner switch, and electron discharge means instantly recognizing a burner operating flame and controlling said relay to open said closedrelay switch and to close said open relay switch.

16. A liquid fuel burner control apparatus comprising a burner, a pump for supplying fuel to said burner, a timer motor having a circuit, a room thermostat to close said circuit, an open shunt switch in shunt circuit with said thermostat, a cam operable by said motor and operable to close said switch, a holding magnet in circuit with said switch, a pressure opened switch responsive to pump fuel pressure and controlling current flow from said shunt switch through said magnet, a second cam operable by said timer motor, a pump motor, a first pump motor switch urged toward open position and movable to closed position and holding relation to said magnet by operation of said second cam subsequent to closure of said shunt switch, a second pump motor switch in series circuit with said first pump motor switch, a closed fiame controlled relay switch in series circuit with said first and said second pump motor switches, means operable by said second cam to close said second pump motor switch, a holding magnet to maintain said second pump motor switch in closed position, a switch in circuit with said room thermostat and closed upon closure of said second pump motor switch to hold said second magnet energized under control of said room thermostat, an open flame controlled relay switch in shunt circuit with said first pump motor switch, electric ignition means to ignite fuel supplied to said burner by said pump and having its circuit controlled by said first-named relay switch, and electron discharge means controlling said relay switches and responsive to a proper burner flame to open said first-named and to close said second-named relay switches, said timer motor opening said shunt switch upon lapse of a predetermined interval thereby to deenergize said first-named holding magnet.

17. A liquid fuel burner control apparatus comprising a burner, a fuel pump for supplying fuel under pressure to said burner, a control switch, timer means energized by closure of said switch and closing for a burner trial starting interval a timer means holding circuit, a, plurality of independently releasable pump switches in series circuit and operable by said timer means, a holding magnet for maintaining closed one of said releasable switches, means responsive to pump pressure indicative of discharge at said burner of an ignitable supply of fuel and operable to deenergize said holding magnet, electrically controlled fuel igniting means energized by closure of said one releasable switch, a flame controlled relay having a closed switch in series with said releasable switches and having an open switch in parallel with said one releasable switch, a holding magnet for maintaining another of said releasable switches in closed circuit position, switch means operable by said timer means to transfer the circuit from said control switch over to said second-named holding magnet, an electron tube in circuit with and blocking current flow through amazes said relay. and means operable instantly upon occurrence of flame to render said tube conductive thereby to energize said relay.

18. A fluid fuel burner controlling apparatus, comprising a flame responsive electron tube relay having a closed starting switch opened by occurrence of flame, a timing means, a main control switch operable upon closure to close a circuit for said timing means through said closed starting switch, a burner motor, a burner motor controlling switch closed by said timing means, an electromagnet to hold said burner motor switch closed and controlled by said main control switch, a switch closed by said timing means and dominating the control of said electromagnet by said main control switch, a burner motor controlling switch closed by said tube relay upon occurrence of flame, and means interconnecting said lastnamed controlling switch and said relay starting switch so that sticking of said last-named controlling switch in closed circuit position will maintain said relay starting switch in open position thereby preventing starting of said timing means.

19. In a liquid fuel burning apparatus, a burner having a fuel supply conduit, 2, pump for supplying fuel under pressure to said conduit, an electric circuit for said pump, means to ignite the fuel discharged at said burner, a timer motor,

circuit controlling means for said electric circuit and including a, switch operable by said timer motor to start operation of said pump, a switch operable by said timer motor and controlling said electric circuit and operable upon expiration of a predetermined interval of timer motor operation to stop operation of said pump, means operable to hold said first-named switch closed upon initial closure of said first-named switch by said timer motor, and means responsive to occurrence of flame at said burner and operable during said interval to establish a circuit in cooperation with said closed switch to render said timer motor ineflective to stop operation of said pump.

20. In a liquid fuel burning apparatus, a burner, a motor, a pump driven by said motor to supply fuel at spraying pressure to said burner, a starting circuit for said motor, means operable at spraying pressure to break said circuit to ultimately deactivate said pump, a running circuit for said motor, an open switch in said running circuit. and electronic tube control means instantly acting upon occurrence of flame at said burner to close said switch.

21. In a, liquid fuel burning apparatus, a burnseries in said circuit, means operable at spraying pressure to open one of said switches to ultimately deactivate said pump, a running circuit for said motor, an open switch in said running circuit, an electronic tube control means instantly acting upon occurrence of flame at said burner to open the other 01' said pair of switches and to close said running circuit switch.

FRED B. AUBERT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,761,018 Martin June 3, 1930 1,963,771 Ballard June 19, 1934 1,877,248 Macrae et al. Sept. 13, 1932 1,818,616 Good Aug. 11, 1931 2,112,736 Cockrell Mar. 29, 1938 1,679,163 Martin July 31, 1928 2,299,501 Schneider Oct. 20, 1942 2,136,256 Sweet Nov. 8, 1938 2,304,200 Plein et al. Dec. 8, 1942 2,261,458 Baile et al Nov. 4, 1941 2,274,384 Scan an Fb. 24, 1942 1,899,744 Breisky et a1, Feb. 28, 1933 1,936,784 Diamond Nov. 28, 1933 2,175,017 Cockrell Oct. 3, 1939 2,343,001 Cohen Feb. 29, 1944 2,253,307 Richter Aug. 19, 1941 FOREIGN PATENTS Number Country Date 298,146 Great Britain Oct. 4, 1928 

